The birth of planetary nebulae, resulting from the death of low and intermediate mass stars, is usually thought of as a slow process, in contrast with the intense supernovae that massive stars produce. But ...

Astronomers using ESO facilities in combination with telescopes in the Canary Islands have identified two surprisingly massive stars at the heart of the planetary nebula Henize 2-428. As they orbit each other ...

Names of astronomical objects are often ambiguous, especially when the historical designation of a certain class of celestial body preceded their physical understanding and was based on their appearance in ...

For many years astronomers have known that young 'protostars' drive supersonic jets of gas from their north and south poles. However, this is the first time that so many of them have been detected at once.

Astronomers using ESO's Very Large Telescope in Chile have captured this eye-catching image of planetary nebula PN A66 33—usually known as Abell 33. Created when an aging star blew off its outer layers, ...

(Phys.org) —Stellar lifetimes are measured in billions of years, so changes in their appearance rarely take place on a human timescale. Thus an opportunity to observe a star passing from one stage of life ...

(Phys.org) —The "butterfly effect" says the flap of a butterfly's wings may lead to a developing hurricane on the other side of the world. But what happens when a butterfly flaps its wings in the depths ...

(Phys.org) —Astronomers know that while large stars can end their lives as violently cataclysmic supernovae, smaller stars end up as planetary nebulae – colorful, glowing clouds of dust and gas. In recent ...

Three thousand light years from Earth, the Cat's Eye Nebula (NGC 6543) is a sight that draws in the human eye. In this image from the NASA/ESA Hubble Space Telescope, numerous bubbles are visible – shapes ...

(Phys.org) —In the spirit of Halloween, scientists are releasing a trio of stellar ghosts caught in infrared light by NASA's Spitzer Space Telescope. All three spooky structures, called planetary nebulas, ...

At a cosmologically crisp one degree Kelvin (minus 458 degrees Fahrenheit), the Boomerang Nebula is the coldest known object in the Universe – colder, in fact, than the faint afterglow of the Big Bang, ...

Improved age data for the Moon suggests that it is much younger than previously believed according to scientists presenting at a Royal Society discussion meeting entitled Origins of the Moon this week (23 ...

(Phys.org) —This new image, snapped by NASA/ESA Hubble Space Telescope, shows the star HD 184738, also known as Campbell's hydrogen star. It is surrounded by plumes of reddish gas—the fiery red and orange ...

Planetary nebula

A planetary nebula is an emission nebula consisting of a glowing shell of gas and plasma formed by certain types of stars when they die. The name originated in the 18th century because of their similarity in appearance to giant planets when viewed through small optical telescopes, and is unrelated to the planets of the solar system. They are a relatively short-lived phenomenon, lasting a few tens of thousands of years, compared to a typical stellar lifetime of several billion years.

At the end of the star's life, during the red giant phase, the outer layers of the star are expelled via pulsations and strong stellar winds. Without these opaque layers, the remaining core of the star shines brightly and is very hot. The ultraviolet radiation emitted by this core ionises the ejected outer layers of the star which radiate as a planetary nebula.

Planetary nebulae are important objects in astronomy because they play a crucial role in the chemical evolution of the galaxy, returning material to the interstellar medium which has been enriched in heavy elements and other products of nucleosynthesis (such as carbon, nitrogen, oxygen and calcium). In other galaxies, planetary nebulae may be the only objects observable enough to yield useful information about chemical abundances.

In recent years, Hubble Space Telescope images have revealed many planetary nebulae to have extremely complex and varied morphologies. About a fifth are roughly spherical, but the majority are not spherically symmetric. The mechanisms which produce such a wide variety of shapes and features are not yet well understood, but binary central stars, stellar winds and magnetic fields may all play a role.